On shafts of periodically operating machines, for example on a crankshaft of an internal combustion engine of a motor vehicle, torsional vibrations occur during rotational motion of the shaft, their frequency changing with the speed of rotation of the shaft. During combustion processes of the internal combustion engine, in particular in traction mode, torsional vibrations are excited in the drivetrain of the motor vehicle. To reduce these torsional vibrations, a centrifugal pendulum may be provided, which can cancel out torsional vibrations over a relatively large speed range of the internal combustion engine, ideally over its entire speed range.
A centrifugal pendulum is based on the principle that because of centrifugal force its pendulum masses attempt to revolve around an axis of rotation at the greatest possible distance when a rotary motion is introduced. The torsional vibrations in the shaft result in an oscillating relative motion of the pendulum masses, while the centrifugal pendulum has a natural frequency proportional to the speed of rotation, so that torsional vibrations having frequencies that are proportional in the same way to the rotational speed of the shaft can be canceled out over a large rotational speed range.
A centrifugal pendulum includes a plurality of pendulum masses, which are suspended on a rotatable pendulum mass carrier by means of guide elements and are able to carry out a motion along specified guideways relative to the pendulum mass carrier, in order to be able to assume a variable distance from the axis of rotation of the pendulum mass carrier while doing so. As a consequence of the torsional vibrations in the drivetrain, the pendulum masses are excited to oscillate or vibrate, while their centers of mass change constantly and time-shifted relative to the torsional vibrations in the drivetrain, which causes a damping of the torsional vibrations due to mechanical feedback. An efficient damping can be achieved through appropriate coordination of the pendulum masses and their guideways.